PkZip

PKZip began life humbly, as PKARC, which was effectively a clone of the ARC file compression utility. Following a legal action with SEA, ARC's developers, agreement was reached allowing one last version of the software using the old file format, and PKPAK was released to an adoring BBS public in 1986. PKWare later developed its own file format, which became immensely popular when the file format was put into the public domain, and BBS users began boycotting the ARC program and using PK programs. The BBS world began to convert all the compressed files from ARC to ZIP format, and ARC slipped into oblivion.

ARC had become popular amongst BBS users, who were paying large amounts of money to transfer files across (by today's standards) painfully slow modems. Any improvement meant money in users' pockets, and tighter compression would mean smaller files, which whipped across the POTS much faster. It's shareware status and simplicity of use were vital to the everyday user, and businesses, recognising its power and versatility began using it to archive data for better storage (necessary in the days of very expensive hard drives.

Phil Katz, the brains behind the company and the product, had already dramatically speeded up the compression process when he developed PKPAK and PKUNPAK, and now began to work on improving the compression algorithm in 1988. Phil was writing in assembly language, and used the best possible algorithms and the 386 processor's features where appropriate. He was still using the LZW algorithm, and whilst he had made improvements in compression and storage techniques, had still not 'invented' compression.

Phil's Zip algorithm was also used in gzip, and remains one of the most the most ported utilities. His improvements to the compression process, and the hatred felt by many toward the creators of ARC meant that the PKZip program had become a standard for the IBM PC under MS-DOS, and even now, remains the most popular file compression algorithm, in many Windows implementations. The MS-DOS version is now at version 2.50, and includes support for long file names.